1. Field of the Invention
The present invention relates to a manufacturing method of a print head for ejecting ink and a print head manufactured by the manufacturing method.
2. Description of the Related Art
An ink jet printing apparatus using a print head for ejecting ink is a printing apparatus of a non-impact type, and has advantages such as high-speed printing, capability of performing printing to various types of printing medium and almost no generation of noises at a printing operation. A representative example in an ejection system of the print head used in this type of ink jet printing apparatus uses electro-thermal conversion elements as ejection energy generating elements. In this system, the electro-thermal conversion element is provided in a pressuring chamber and an electrical pulse as a printing signal is applied to the electro-thermal conversion element to give thermal energy to ink, thereby using an air bubble pressure at foaming (at boiling) of ink generated due to a phase change of the ink at that point, for ejecting the ink. As a structure of the print head using these electrothermal conversion elements, there is known a system for ejecting ink in parallel to a substrate in which the electro-thermal conversion elements are arranged (edge shooter type). In addition, as the other structure, there is known a system for ejecting ink perpendicularly to a substrate in which the electro-thermal conversion elements are arranged (side shooter type).
The conventional example in regard to a manufacturing method of this type of ink jet print head is as follows. First, heating resistors constituting electro-thermal conversion elements and conductor wirings for supplying power to the heating resistors are provided on a silicon substrate, and a protective film is provided on the conductor wirings. Thereafter, a pattern for an ink passage and a pressurizing chamber is formed by patterning of resist. Next, an ink passage forming material is coated and patterned, and the forming member for the ink passages including ejection openings and the like are provided. Thereafter, holes for supplying ink from a backside of the silicon substrate to the ink passages are formed in the silicon substrate. The resist is removed through the holes thus formed to complete formation of the ink passages including the ejection openings and the like. A flexible substrate for electrical connection of a printing element substrate to an apparatus main body is connected to the printing element substrate on which the ink passages including the ejection openings and the electrothermal conversion elements are thus provided.
FIGS. 1A to 1D are views showing a conventional example of a series of print head manufacturing processes as described above. As shown in FIG. 1A, first, a support plate for supporting the above-described printing element substrate is formed by joining a plate 16 and a plate 16A together. Next, as shown in FIG. 1B, the printing element substrates 100C and 100Bk as described above are joined to the plates 16 and 16A. Then as shown in FIG. 1C, a flexible wring substrate 11 which has openings surrounding respectively the printing element substrates 100C and 100Bk is joined on the support plate. Finally, as shown in FIG. 1D, electrical connection parts between the printing element substrates and the flexible wiring substrate are sealed by sealants 20A and 20B. More specifically, plating or a bowl bump is formed on a pad on the printing element substrate and then to the plating or the bowl bump, an inner lead wire at a side of the flexible wiring substrate is connected. In addition, for sealing this connection part, an inner lead bonding (ILB) sealant (electrical connection part sealant) is applied.
The sealants which are used in the electrical connection part between the printing element substrate and the flexible element substrate and which are provided at an upper side and a lower side of the inner lead wire are required to have properties which are different between the upper side and the lower side of the inner lead wire. More specifically, the sealing at the lower side of the inner lead is required so that the sealant passes through between the inner lead wires, flows along the inner lead wire and enters in until a backside of the inner lead wire for appropriately performing the sealing. Therefore, it is preferable that the viscosity of the sealant is low. On the other hand, in regard to the sealing at the upper side of the inner lead wire, it is preferable that the viscosity of the sealant is high and, after the curing, the sealant has a high resiliency. This is because appropriate sealing at the upper part of the inner lead wire is required to be performed so that the sealants stay in more than a given amount at the upper side of the inner lead wire. If the viscosity of the sealant is low, the sealant in amounts more than necessary may flow out from the upper side of the inner lead wire, and the sealing at the upper part on the inner lead wire may not be sufficiently performed. In addition, when the periphery of the ejection openings in the print head is wiped, the sealant at the electrical connection part is rubbed by the blade. For improving the durability in the sealant against this rubbing, it is preferable that the sealant has a high resiliency after the curing.
For the reason as described above, it is known that two kinds of adhesives are used as the sealant. FIG. 1D shows an example using the two kinds of sealants 20A and 20B.
However, use of two kinds of the sealants in regard to the viscosity of the sealant as described above possibly raises the problem that the manufacturing process composed of a coating process of the sealant and the subsequent process of thermal curing of the sealant is complicated. Particularly because of continuously using sealants having different properties, the condition of the thermal curing is supposed to be more precise. Further, in a case where the curing state of the sealant is unstable since the precise condition of the thermal curing is not satisfied, the sealing effect may be inappropriate by the melting of two kinds of the sealants with each other.
For overcoming such a problem, Japanese Patent Laid-Open No. 2004-351754 describes a technology in which one kind of a sealant is used and also a requirement for the sealant at the upper side of the inner lead wire is satisfied by a cover member separately provided. More specifically, as shown in FIGS. 2A and 2B, cover members 21 are provided for covering an entirety of the inner lead wires, and one kind of the sealant is poured inside the cover member 21 to be cured.
However, in the method described in Japanese Patent Laid-Open No. 2004-351754, it is required to additionally provide the cover member. Inconsequence, it raises the problem with an increase of the number of the process and complication of the print head structure.